The US National Grid (USNG) is a ground-based gridded coordinate system based on the Universal Transverse Mercator (UTM) System.  As such, the basic unit of measure is the meter and positions are reported as distance north from the equator (Northings) and distance from the zone central meridian (Eastings).  The purpose of USNG is to provide a seamless, standardized system of reference for nationwide use during times of crisis.  The content of this section describes the development, standards, and application of USNG.

The map below is an example of an USNG implementation for New Orleans, LA.  Note that even though there is a zipper effect at the junction of two grid zone designators, the longitudinal coordinates may still be easily distinguished from one another.